In water softening, utilizing the zeolite or ion exchange process, divalent or hardness, calcium and magnesium ions are replaced by monovalent ions. In the case of a sodium form water softener the hardness ions are replaced by sodium ions. This leaves a product water or outflow from the water softener that has a very slight conductivity difference from the hard water feed. The problem is compounded if the feed has a high sodium ion background, as the conductivity differences between product and feed will be minute.
The renders difficult the detection of water softener exhaustion by merely measuring the conductivity of the effluent.
It is accordingly an object of the invention to provide a system for detecting exhaustion of a water softener and controlling the regeneration thereof which does not depend upon high degree of sensitivity in the measurement of product conductivity or continuous recalibration under various conditions of operation which would be necessary in the utilization of highly sensitive conductivity measurement instruments.
Other and further objects, features and advantages will become apparent as the description proceeds.